The Sauerbraten (Cube 2) engine is an advanced and complete originally open source engine available today, with many novel features unavailable elsewhere. Its main strength is its very productive content pipeline which is especially attractive to smaller companies making casual or serious games. Read more

an on-going effort to develop a lightweight, secure virtual machine for executing Java bytecode. The VM is intended to be an extension framework for applications or devices that dynamically load and execute untrusted extensions

C# Java Virtual Machine is a tiny implementation of the Java VM, including simple native classes. It written using the C# language. The VM is very easily expandable by writing additional native or Java classes.

A research Java Virtual Machine developed at the Vienna University of Technology and released under the GPL. The VM uses a compile-only approach, which means there is no interpreter available. The optimizing JIT compiler is available for a number of architectures.

conforms to the JVM specification version 2 (blue book). In comparison to most other VM's (free and commercial) it is extremely small, with a stripped executable on PowerPC of only ~90K, and Intel 70K. However, unlike other small VMs (e.g. KVM) it is designed to support the full specification, and includes support for object finalisation and the Java Native Interface (JNI)

Java PathFinder (JPF) is a system to verify executable Java bytecode programs. In its basic form, it is a Java Virtual Machine (JVM) that is used as an explicit state software model checker, systematically exploring all potential execution paths of a program to find violations of properties like deadlocks or unhandled exceptions.

JavaDesktopEngine is a Java engine capable of running several programs within the same VM instance, without launching lots of VMs for simple processes. Services exposed can be accessed by trivial XML-RPC calls.

a Java 2 (JDK 1.3) compatible virtual machine. joeq is unique in that it is entirely implemented in JavaTM, leading to greater reliability, portability, maintainability, and efficiency. It is also language-independent, so code from any supported language can be seamlessly compiled, linked, and executed --- all dynamically